D.C. Mun. Regs. tit. 14, r. 14-703
All gutters and downspouts shall be properly connected, and shall be maintained in good condition, free of holes and obstructions.
Water shall be conveyed off premises in accordance with the plumbing regulations of the District of Columbia.
The owner of any premises used in whole or in part for residential purposes shall cause the yard or area at the premises to be graded and paved so that all drainage flows freely from all parts of the premises into any sewer traps which may have been provided for that purpose.
If there are no sewer traps, the drainage shall flow away from any inhabited building on the premises.
Yard spaces and other areas appurtenant to a residential building shall be graded by the owner to avoid the accumulation of water.
D.C. Mun. Regs. tit. 14, r. 14-703